The present invention relates to a filter with a filter housing formed of multiple parts, including a filter head connectable with a filtering pot. The housing receives at least one filter element including a support tube surrounded by a filter mat provided at its free ends with filter element mountings. At least one of the filter element mountings is connected securely with the support tube and can be brought into contact with the filter head. At least at the end of the filter mat which has the filter element mounting connected with the filter head, an intermediate spacing member is arranged between this filter element mounting and this end of the filter mat. The intermediate spacing member can be removed together with the filter mat from the support tube, which remains connected with the filter head.
Filters, as disclosed EP 0 547 291 A, serve mainly to decontaminate contaminated fluid, especially hydraulic oil, by removing the contaminants. For this purpose, the contaminated fluid passes through an inlet opening into the filter arrangement and flows through the filter from the exterior to the interior. The filter mat is supported on the support tube constructed in the form of a hollow cylinder with apertures. The contaminants remain in the filter mat, and the fluid cleansed of its contaminants is discharged from the filter arrangement through a discharge opening. If the filter mat is obstructed by the contaminants, which can be determined generally by a rise of the differential pressure, then, with the conventional arrangements, the filter must be exchanged for a new filter.
For the exchange of the filter element, the filtering pot is unscrewed from the filter head and the filter mat obstructed with contaminants is exchanged for a new one. The contaminated filter mat is removed from the support tube along with its intermediate spacing member, while the support tube remains on the filter head, together with the associated filter element mounting. The costs involved in a filter mat exchange are thus reduced and the environment is less contaminated in the process, since the filter mats in question are recyclable without further treatment.
With very high fluid differential pressures, however, problems arise in these conventional arrangements in the area of the filter element mounting, because of the low support forces present at that point. The low support forces can lead to failure of the entire filter arrangement. The effectiveness of the sealing in the vicinity of the mounting can be reduced and leakage cannot be avoided. Furthermore, there is the possibility of impacting or buckling of the filter assembly with the drawbacks which that entails.
Objects of the present invention are to provide a filter arrangement that avoids the aforementioned drawbacks in conventional filter arrangements.
The foregoing objects are basically attained by a filter arrangement having a multi-part filter housing, a filter element, first and second filter element mountings, a first intermediate spacing member, and a first axial gap extending between the first intermediate spacing member and the first filter element mounting. The filter housing includes a filter head detachably coupled to a filter pot. The filter element includes a support tube surrounded by a filter mat, with the mat being open at opposite first and second ends. The filter element mountings are mounted on the respective ends of the filter mats. The first filter element mounting is securely connected with the support tube and contacts the filter head. The intermediate spacing member is coupled to filter mat first end, is removable with the filter mat from the support tube when the support tube remains connected with the filter head, and is mounted between the filter mat first end and the first filter element mounting. The axial gap forms a first possible fluid passage point at the first filter element mounting, which gap is closed by fluid differential pressure generated after operation start-up of the filter arrangement.
Closing the gap by the resulting fluid differential pressure following the start-up of operation provides axial support of the end caps of the cylindrical filter element and guarantees that the high differential pressures are overcome. Furthermore, following closing off of this possible fluid passage point by means of the prebiasing or preloading caused by the fluid differential pressure, higher quality sealing occurs in the vicinity of the filter mounting, so that leakage is avoided. With sufficient prebiasing of the filter assembly, the gap can be deleted, while a theoretical passage point nonetheless remains.
The filter mats which are used can be produced either with or without supporting meshing made of simple paper elements. Higher quality support elements incorporate a multi-layer mat construction made up of a variety of materials. The filter mat can also be designed to be pleated.
In one preferred embodiment of the filter arrangement according to the present invention, the prebiased filter element mounting connected with the filter head is an integral component part of the filter housing or with radial prebiasing can be moved forward onto an interior support of the filter head. With the integrated arrangement, the filter element mounting turned toward the filter head together with the support remains in any case on this member. With forward movement of the filter element mounting on an associated interior support of the filter head, the filter element mounting is detachably connected with the filter head and can be removed together with the support tube. An O-ring, which is prebiased between interior supports of the filter head and the filter element mounting, can serve to produce the raidal prebiasing.
In another preferred embodiment of the filter arrangement according to the present invention, the intermediate spacing member, arranged between the end of the filter mat and the filter element mounting connected with the filter housing, overlaps this filter mat end in a cap-like manner. The intermediate spacing member is detachably connected with the filter element mounting, preferably by means of a clamp ring. In this manner, the intermediate spacing member, either additionally or alternately in an axial mounting arrangement, has an elastically flexible sealing, which can be brought into contact with the filter element mounting. In this configuration, after release of the clamping ring, the filter mat together with the intermediate spacing member can be removed from the filter element mounting and the support tube.
In another preferred embodiment of the filter arrangement according to the present invention, the filter element mounting connectable with the filter head incorporates cam drive elements, which can be brought into contact with the filtering pot under the effect of an outside power source. With smaller relative movement of the filter element relative to the filtering pot, and with simultaneous screwing up and down of the filtering pot, the filter element can be removed from the filter housing or inserted therein. Insofar as the aforementioned cam drive elements are part of at least one intermediate spacing member, the filter element mounting in turn can remain with the support tube in the housing. Only the filter mat is removed with the intermediate spacing members connected with it.
Preferably, in this manner, the end of the filter element remote from the filter head is closed off by a filter element mounting constructed of a plurality of parts. The associated intermediate spacing member then surrounds it in a cap-like arrangement. Preferably, the intermediate spacing members can in turn be caught and held together with the associated filter element mounting by means of a catch connection.
In one further preferred embodiment of the filter arrangement according to the present invention, a power source is inserted between support tube and filter head of the filter housing, usually in the form of a tension or compression spring. Another power source is located, preferably between the filter pot and the filter element, and is usually a compression spring, working on the filter element mounting remote from the filter head. In this manner, even during increasing compression or impacting stress on the filter element, impacting or thrust-driving of the exchangeable filter element to be inserted in axial alignment can be prevented, which if necessary for the exchange would lead to damage.
The present invention furthermore relates to a filter element for use in a filter arrangement as described above, wherein the filter mat is configured as a hollow cylinder with an intermediate spacing member mounted on at least one end. Together with the filter mat, the intermediate spacing member can be removed or can be moved forwardly by sliding onto a support tube. The filter, designed and constructed as a modular element, can thus be used again together with the support tube and the filter element mounting. When the filter material becomes obstructed by contaminants, the depleted hollow cylindrical filter need simply be exchanged for a new one in a manner which is low cost and environmentally safe.
As a result of the arrangement having the support tube closed off at the bottom end in connection with an elastic end cap or in connection with a catch arrangement or limiting boss arrangement for the end cap, a rigid support in axial alignment is obtained. Especially at high pressures, it guarantees reliable function of the filter arrangement.